Color images are customarily obtained in the photographic art by reaction between an oxidation product of a silver halide developing agent and a dye-forming coupler. Pyrazolone couplers are useful for forming magenta dye images; however, such couplers have shortcomings with respect to color reproduction in that the unwanted absorption around 430 nm causes color turbidity. Bicyclic pyrazolo couplers, particularly pyrazolotriazole couplers, represent another class of couplers for this purpose. Examples of bicyclic pyrazolo couplers are described in, for example, U.S. Pat. No. 4,443,536; U.S. Pat. Nos. 1,247,493; 1,252,418; and 1,398,979; and U.S. Pat. Nos. 4,665,015; 4,514,490; 4,621,046, 4,540,654; 4,590,153; 4,822,730 and European Patents 177,765 and 119,860. One class of pyrazolotriazole couplers includes 1H-pyrazolo[3,2-c][1,2,4] triazole couplers and another includes 1H-pyrazolo[1,5-b][1,2,4] triazole couplers, such as described in European Patent 177,765. While these couplers have a reduced level of unwanted absorption, the conversion of the coupler into an azomethine dye is slow and the maximum attainable density is reduced due to lower coupling efficiency. The aforementioned U.S. Pat. No. 4,822,730 discloses pyrazolotriazoles having a group expressed by the formula --(A)L--B where L represents --N(R)SO.sub.2 --, --SO.sub.2 N(R)--, or --N(R)SO.sub.2 N(R)--. The compounds exemplified contain a methyl or unbranched alkyl group at the 6-position rather that a fully substituted carbon. For example, the following compound is suggested: ##STR1## These couplers do not fully satisfy the needs for activity and color reproduction.
Bicyclic pyrazolo couplers containing a t-butyl group at the 6-position are described in U.S. Pat. No. 4,882,266. An example of such a coupler is: ##STR2## Such couplers suffer from the disadvantage of lower coupling reactivity than the methyl analogs and also exhibit less light stability than the couplers of the invention.
U.S. Pat. No. 5,066,575 discloses pyrazolotriazole couplers having a branched alkyl at the 2-position such as the following: ##STR3## Photographic elements employing these couplers are unsatisfactory with regard to dye-light stability.
Finally, in copending application U.S. Ser. No. 07/841,461, filed Feb. 26, 1992, there are disclosed pyrazolotriazole couplers containing a ballast having a carbon alpha to the carbonyl function which carbon has both an aryloxy and a sulfone substituent. Such a coupler is shown in Comparative C-3 of the specification. These materials are unsatisfactory because of the difficulty of synthesizing compounds with these two substituents on the alpha carbon.
While such magenta dye-forming couplers are useful in photographic silver halide materials and processes, many of such couplers do not have sufficient coupler reactivity. Moreover, the existing products are deficient with respect to obtainable speed, dye light stability, and color reproduction. A problem to be solved is to provide an element which has both sufficient dye-light stability without sacrificing the color reproduction properties.